Electric overload circuit breaker



Feb. 25, 1958 R. c. Imcawla-RSENv 2,824,931

ELECTRIC ovERLoAn CIRCUIT BREAKER,

misa wapen 7. 1955 s sham-sheet 1 IINVENTOR BY M J a TroRNEY Feb. 25,1958 R. c. INGwERsEN ELECTRIC OVERLOAD CIRCUIT -BREAKER Filed March '7,195s 3 Sheets-Sheet 2 Wwwldl ,W

INVENTOR M C.

mk-.I ATTORNEY Feb- 25, 1958 R. c. lNGwERsEN ELECTRIC ovERLoAD CIRCUITBREAKER 5 Sheets-Sheet 3 Filed March 7. 1955 INVENTOR MJ C. 557m- BYATTORNEY United States Patent() ELECTRIC OVERLOAD CIRCUIT BREAKERRichard C. Ingwerseu, Jackson, Mich., assignor to Mechanical Products,Inc., Jackson, Mich., a corporation of Michigan Application March 7,1955, Serial No. 492,508 7 Claims. (Cl. 20D-116) This invention relatesto electric circuit breakers which are capable of being employed asmechanical on and off switches but which also have automatic currentoverload protection due to the action Vof latch means by which fixed andmovable contact means are maintained in the closed position but whichlatch means is responsive to the current, conducted in the circuitclosed by said contacts, to free the movable contact means to moveautomatically to open position upon the occurrence of a predeterminedcurrent overload.

The prior art circuit breakers employ an actuator in the form of arectilinearly slidable plunger which is actuatable in the manner of amanual push and pull button to close and open the circuit at thecontacts, respectively, and which plunger is operatively connected withthe movable contact means and with a bimetallic latch in such mannerthat when the plunger is pushed-in the movable con-tact means is closedagainst the fixed contact means vand the latch is set into position tohold the contacts closed, whereas when the plunger is pulled-out thecontacts are opened. Further, the construction and arrangement of saidprior art circuit breakers was such .that upon the latch beingautomatically actuated to open the contacts the plunger moves to anoutwardly projected position in which a marking thereon, such as acolored band, is brought into view to indicate that the circuit has beeninterrupted.

An objection to these prior art circuit breakers is that there is thepossibility of the plunger being pushed farther in than its normalpushed-in and circuit closing position, due for example, to someoneinadvertently brushing against the plunger, with the result that thecircuit was unintentionally opened, while, further, there is nothing tdistinguish whether the circuit has been opened due to overload, or dueto manual actuation of the plunger.

An object ofthe invention is to provide a push-pull and automaticcurrent overload circuit breaker of the above described kind in which,when the plunger has been moved to close the contacts, further inwardpressure on the plunger merely tends to effect closer engagement of thecontacts.

Another object of the invention is to provide a circuit breaker of theabove kind in which the movement of the plunger is arranged to takeplace in such manner as to indicate whether the circuit has beeninterrupted due to the occurrence of current overload, or due to manualactuation of the plunger.

Yet a further object of the invention is to provide an electric circuitbreaker of the above kind in which 'the overall Vsize of the circuitbreaker can be considerably reduced compared with the `prior art circuitbreakers.

Further objects and advantages of the present invention, 'residing inthe construction, arrangement and combination of `parts will beunderstood and appreciated from a consideration of the followingdescription with reference to the accompanying drawings and from theappended claims.

In the drawings:

Fig. 1 is an elevational view looking upon the inside of one of the twocasing sections of a circuit breaker and switch in accordance with theinvention, with the circuit breaker and switch mechanism in positiontherein and the contacts closed,

Fig. 2 is a cross section on the line II-ll of Fig. l,

Fig. 3 is a similar View to Fig. l but showing the parts in the contactopen position, due to overload.

Fig. 4 is a similar view to Fig. 3 showing the parts in the contact openposition due to manual actuation of the actuator plunger,

Fig. 5 is a similar view to Fig. l but of an alternative construction inwhich the actuator plunger is arranged to move in reverse sense to thearrangement according to the previous figures, and

Fig. 6 is a cross section on the line V V of Fig. 5.

Referring to Figs. l to 4 of the drawings, 10, 10 indicate a pair ofsimilar casing sections of electrical insulating material which are heldsecured together, as by bolts l2, and which casing sections combine toform an enclosed interior space 14 in which the automatic overloadcircuit breaker and manual switch mechanism is mounted and secured inoperative assesmbly.

At one end, the casing sections define an opening 16 through which thecyiindrical end portion 20a of an actuator plunger 20 extends to theoutside of the casing and carries an actuator button 2Gb axially spacedfrom a collar 29e by an indicator ring 20d which ring 20d vis of somedistinctive color (being white, for example, and the collar 26e beingred) so that, in this particular embodiment ot the invention, when thesaid ring 20d is visible, as wiil be described later, this denotes thatthe switch is 'in the on position and that the bi-metallic latch is alsoin the engaged position.

The plunger is formed with a ange portion 20e vand another and adjacentilange part Ztf. Flange Zilf lhas one end of a pair of coil springs 22anchored thereto, the opposite ends of which springs are anchored toears 24:1 bent out from transverse bridges 24h which interconnect a pairof paraliel spaced apart bi-metailic and U-shape latch parts 24, saidears, bridge portions and latch parts being of integral construction andforming a unitary latch and movable Contact assembiy, indicated `parts24 with abutment ledges 28a defined at the free ends of a pair of wearresistant plates 28 secured, with initial ension, against opposite sidesof the plunger portions 26, as by the rivet 39.

The plunger parts 20a, 201:, 20c and 26d are shown separately formed andconnected together by an axial screw 32, the head 32a of which isaccessible at the outer end of the button 2tb and which screw is screwedinto the upper end of the plunger portion 2.6, as indicated at at 32b.The abutment plates 28 have inturned ears 2812, which may be of curvedsection to give them lateral stability, and between which the taperedlower end 32e of .screw 32 engages, 'said screw being mounted in anaxial bore 36 in the plunger portion 2b and being accessible foradjustment through said bore. By adjustment of the screw 32 it ispossible to cause the abutment ledges 28a to move laterally outwards orinwards with respect to the edges 24C of the latch parts 24 and therebyadjust the extent to which said edges must travel before the latch partsdisengage the abutinents. Such adjustments would be effected uponinitial assembly of the parts, if tests indicated that adjustment shouldhe 3 made, and enables the unlatching action to be controlled withinfine limits.

The latch parts 24 carry a pair of laterally spaced electrical contacts38, which are the movable contacts, and cooperate with companion fixedelectrical contacts 40 to close the electrical circuit involved.

As distinct from the prior art constructions in which the movablecontacts were carried at the outer ends of relatively long ilexibleconductor arms secured at their inner ends to the bridge portions of theU-shape latch parts, with the present construction the said conductorarms are eliminated and the movable contacts 38 are immediately fastenedupon the bridge portions 24b through the medium of intermediate plates42 having end portions 42a which, as seen in Fig. 2,.project beyond theconfines of the engaged xed and movable contacts and serve as battles toprotect the bi-metallic parts 24 from direct attack by the flame and gasevolved, due to arcing. when the circuit is suddenly interrupted. aswill be described. The plates 42 may be of stainless steel.

By eliminating the said conductor arms the important advantage isgained, compared with the prior art circuit breaker that the overallwidth of the circuit breaker can be reduced to as much as one half sizeand enable two circuit breakers according to the present construction tobe mounted side by side upon a panel to occupy approximately the samespace as the prior art circuit breaker.

At its lower end. as seen in Figs. l and 2. the plunger portion isformed with fork prongs 44 between which a transverse pin 46, securedbetween the casing sections, is located to guide the fork prongs, andhence the plunger, for rectilinear sliding motion with respect to thecasing opening 16 and the interior casing guide surfaces 48 seen at thelower end of Fig. 1.

The fixed contacts 40 are shown mounted within and upon the casing bybent conductor strips 50 carrying the terminal posts 52.

Fixedly mounted within a cavity 54 at the upper end of the casinginterior there is a sheet metal plate part 56 from which a pair ofdiagonally opposite flexible blades 58 depend, said blades being guidedthrough slots 60 in the plunger flange 20e and being formed withinwardly directed opposed angular portions 62 which have cammingengagement with the inner ends of said flange slots and serve to retainthe plunger in the contact open position when the plunger is actuated inthe manner of a push-pull switch, as will be described later.

A coil spring 64 is mounted about the plunger and engages between theupper interior wall surface of the casing and the flange 20e. Thisspring 64 constantly urges the plunger 20 inwardly with respect to thecasing and maintains the contact pressure.

A metal cap 66 secured upon the exterior of the casing at the upper endthereon, in the position as shown in the drawings, carries an exteriorlyscrew-threaded boss 68, through which the plunger part 20c passes andwhich boss carries a nut '7.0 by which the circuit breaker can bemounted in a desired location.

72 indicates ledge surfaces or abutments within the casing interior withwhich the bridge parts 24b of the bi-metallic latch parts engage toarrest movement of these parts in the circuit opening direction. Inoperation, with the parts as show n in Figs. 1 and 2, the'plunger is ina pushed-in position in which the plunger indicator portion 20a' isvisible, the plunger flange 20e is located beneath the spring bladeangle portions 62, the contacts 38 and 4t) are closed, the bimetalliclatch parts 24 are engaged with the abutment ledges 28a and, as theresult, the springs 22 are tensioned. With the parts thus positioned,upon a current overload condition, to which the bi-metallic parts 24have been calibrated, being reached, the parts 24, due to heating by theconducted current, and their bi-metallic aangaat characteristic, willautomatically disengage the abutment ledges 28a, with the result thatthe tensioned springs 22 operate immediately to move the latch parts 24and movable contacts 42 upwards (in the position as shown in Figs. 1 and2), with sudden breaking of the circuit at the contacts 38 and 40Vandmovement of the plunger downwards due to the action of the spring 64.Said upward movement of the parts 24, and hence the movable contacts 38,isrrelative to the plunger and is arrested when the bridge portions 24bof the latch parts arrive against the ledges 72, whereas the resultingdownward movement of the plunger causes the indicator portion 20d todisappear from sight by its passage into the boss 68. The plunger isbrought to rest in its inward position by thel arrival of the plungerfork prongs 44 against the bottom and interior casing surface 47.

Fig. 3 shows the position of the parts when the contacts havebeen'opened due to current overload;

With the parts as seen in Fig. 3, to re-set the bimetallic latch parts24 against their abutment ledges 28a the plunger is pulled outwardsagainst the action of the spring 64 until the abutment ledges 28a arebrought opposite the vedges 24C of the latch parts, whereupon theseedges, due tothe inherent springiness thereof, move into engagement withthe abutment ledges. The latch parts arethen re-united with the plunger,at which time the plunger will be held in an extended position due tothe plunger flange 20e being on the upper side of the angular portions62 of the blades 58. To close the contacts, therefore, the plunger mustbe pushed-in to Ymove this ange 29e to the opposite side of the angularportions 62, at which time the spring 64 is free to take over, and carrythe movable contacts 42 back into engagement with the iixed contacts 40.The parts will then be in the position shown in Fig. l.

To open the ccntact assembly manually, with the parts .as indicated inFigs. l and 2, the plunger 2t) is pulled upwards (in the position asshown) against the action of the spring 64 but in this instance thelatch parts 24 will .remain in engagement with their abutment ledges 28a.and will move as one with the plunger, until the contact plates 42 arebrought against the ledges 72. While this movement is taking place theplunger flange 20e will pass upwardly beyond the angular portions 62 ofthe spring blades 58, with the result that at the time when the contactplates 42 are arrested against the ledges 72 the plunger iiange 20e willbe positioned above the said angular` portions and will hold the plungerin its outwardly projected position in which both the plunger portions20d and 20care in sight and reveal that the contacts have been openeddue to manual actuation of the plunger.

As above indicated plunger portion 20d can be colored white and portion20c red. Thus, an observer looking at the circuit breaker with the partspositioned as shown lin Figs. l and 2 will see only the white banddisplayed by plunger portion:20d, thereby indicating that the contactsare closed. With the parts as seen in Fig. 3, plunger portion 20d ishidden within the casing and only the plunger portion 20b is seen. Thisplunger portion will be'inits natural color, such as black. With theparts as seen in Fig. 4, both the plunger portions 20d and 20c will beoutside the casing i. e. the White and the red portions. Accordinglywhen neither the white nor the red is seen an observer knows thatthecircuit breaker has been actuated due to overload. When the white onlyshows he knows that the circuit breaker has'been reset and is in contactclosed condition. When both red and white are shownV he knows that thecircuit breaker has been manually opened. This visible indicationof-whether the circuit breaker has been opened d ue to overload ormanually is an important feature. Y Y Y With the contacts closed as seeninl-Figs. l andv 2, pressure against the plunger head 32a will notseparate the contacts but, due to the rigid connection involved, willincrease the pressure at the closed contacts 38 and 40. This is anladditional important feature of this circuit breaker.

i Thecircu't breakeraccordingto Figs. 5 and'6 possesses the advantagesof the already described circuit breaker but with the plungerA motiontaking place in the reverse sense.

' According to Figs. 5 and 6, the plunger spring 72 operates toconstantly urge the re-set actuator plunger 74 outwardly'with respect tothe casingV 76 with the result that whenl the bi-metal latch parts 78leave the abutment ledges 80 due to the occurrence of overload theplunger will be projected outwardly to the dotted position A where itwill be held due to the engagement of a flange plate 82 on the plungerwith the inside casing surfacesl 84.

With the circuit breaker set in the contact closed position as seen inFigs.'5 and 6 the'slottediflange 86 on the -plunger is located onkone'side (the top, as shown) of which the projecting plunger end is inthe full line position, to open the contacts 90 manually the plungermust be pushed in to the second dotted position B. In so doing the latchplates 78 will remain set upon the abutment ledges`80 so that theplunger, latch plates and abutment ledges move as one. At the same timeas the movable Ycontacts and latch assembly are moved against the stopsurfaces92 within the casingtheV slotted plunger flange 86 will beforced pastthe angular portions 88a of the flexible blades 88. Thus,when the contacts have been moved to the open position by manuallypushing the plunger 74 inwards the plunger willrbe held in the inwardlydepressed position by the engagement of the flange 86 beneath, saidangular portions. It will be appreciated therefore that the principle ofoperation of this circuit breaker is the same as that according to Figs.l to 4 but that the plunger movements take place in the reverse sense.By appropriate coloring of the plunger with bands as described withreference to Figs. l to 4 it is possible to determine at a glancewhether the breaker contacts have been opened due to overload or due tomanual actuation.

Having thus disclosed my invention, what I consider as novel, and wishto secure by Letters Patent, what I claim is as follows:

l. In a manually operable switch having automatic current overloadprotection, the combination with an actuator plunger for moving movablecontact means into closed or open position with respect to fixed contactmeans, said contacts being within a casing structure, of means mountingsaid plunger for rectilinear motion with respect to said casingstructure, said plunger including an end portion projecting to theoutside of said casing and said mounting means including spring meansacting to urge said plunger in one direction with respect to saidcasing, said movable contact means being connected with latch meansresponsive to the conducted current and said actuator plunger includingan abutment for said latch means, said latch means being automaticallyreleasable from said abutment upon the occurrence of a predeterminedoverload current, and said casing including means engageable with saidactuator plunger to maintain the plunger in a first position in whichsaid contacts are closed and said plunger projects a certain distanceoutside said casing, said spring means being operative to move theplunger to a second position, upon release of said latch from saidabutment, in which said plunger projects a different distance outsidethe casing than said certain distance.

2. An electric current breaker having fixed and movable contacts and abi-metal latch structure operatively connected with said contacts tohold the same engaged,

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.said latch structure being responsive to the conducted current to.automatically open the circuit at said contacts upon the occurrence of apredetermined current overload and actuator meansbeing provided tore-setthe contacts and latch structure in. circuit closing position, saidactulator means being manually actuatable to open the circuit linearmotion with respect to casing structure containing said contact means,said plunger including an end portion projecting to the outside of saidcasing and said mounting means including spring means acting to urgesaid plunger inwardly with respect to said casing, said movable contactmeans being connected with latch means responsive to the conductedcurrent and said actuator plunger including an abutment for said latchmeans, said latch means being automatically releasable from saidabutment upon the occurrence of a predetermined overload current, andsaid casing including stop means engageable with said actuator plungerto maintain the plunger in a first position in which said contacts areclosed and said plunger projects a certain distance outside said casing,said spring means being operative to move the plunger to a secondposition, upon release of said latch from said abutment, in which saidplunger projects a different distance outside the casing than saidcertain distance,

said plunger being movable past said stop means by manual actuation ofthe plunger with attendant opening off the contacts, said manualactuation being against the action of said spring and said stop meansarresting the plunger in an open contact position in which the plungerprojects yet a different distance outside of casing than said certaindistance.

4. An electric circuit breaker, comprising in combination fixedelectrical contact, a movable electrical contact in opposed relation tosaid fixed Contact, structure supporting said movable contact formovement toward and from said fixed contact, latch means for releasablyholding the movable contact against the fixed contact, said latch meansbeing in electrical connection with said contacts so as to be responsiveto the conducted current for actuating said latch means to release themovable contact for movement away from the fixed contact upon theoccurrence of current overload, actuator means, said actuator meansbeing actuatable to set said latch means in position to hold the movablecontact against the fixed contact, and means mounting said actuatormeans for inward movement with respect to the casing upon release of thelatch due to current overload, means mounting said actuator means forlimited inward movement with respect to the casing to set said latch inposition to hold the movable contact against the fixed contact, saidmounting means including spring means connected with said actuator meansto cause the actuator means to move farther inwards with respect to thecasing upon the occurrence of current overload, said actuator mountingand spring means permitting said actuator to be manually actuated torelease said latch means from contact engaging position independently ofsaid current overload.

5. 1n an electric circuit breaker, casing structure, a fixed Contact insaid casing, a movable contact in the casing adapted to make and breakelectrical contact with the fixed contact, a contact reset actuator,spring means mounting said actuator in the casing for rectilinearmovement constantly into the contact opening position, a thermalresponsive latch connected with said movable nemesi 'actuator torestrain the Amovable contact-latch unit and actuator to have unifiedmovement with respect to the iixed contact and in the contactopening'direction, a second spring means connecting said movablecontact-latch unit with said actuator and operable toV break theelectrical contact with a snap action when the latch is disengaged fromthe actuator, said second spring meansbeing stressed when Ytheelectrical contact is made consequent upon relative movement betweensaid contact-latch unit and said plunger, an abutment on said casingstructure limiting said snap action movement of the movablecontact-latch unit and an abutment limiting movement of said actuator byits said spring mounting means when the latch is disengaged.

electrical contact supported in said casing for movementV into and outof engagement with said fixed contact, actuator means movably supportedin said casing, means operatively connecting said movable contact meansand said actuator means so that said actuator means can be manuallyactuated to move said movable contact means into and out of engagementwith said fixed contact means while said movable contact means can alsomove relative to said actuator means upon occurrence of current overloadto permit said movable contact means to move out of engagement with saidfixed contact means, means supporting said actuator means in said casingso that said actuator means will move in one direction inV said casingupon the occurrence of a current overload and in an opposite directionupon manual actuation to move said movable contact means away from saidfixed contact means whereby to indicate whether the movable contactmeans have been moved to open position due to the occurrence ot currentoverload or due to manual actuation of said actuator means.

" '7; Ane'lectrie circuit breaker including a casing, fixed .electricalContactin.-saidrcasingrn ,eltficl Conta@ mov.

ably supported in said casing for movement into -and out -ofengagementiwithsaid fixed contact, latch means for lreleasably'holclingsaid` movable contact in engagement with said fixedcontact, said latchmeans being in electrical connection with said movable contact so as tobe responsive to conducted current for actuation to release the saidmovable contact for movement away from said fixed contact upon theoccurrence of current overload, actuator means movably supported in saidcasing for in and out movement, means operatively connecting saidactuator means and said latch means so thatmanual movementof saidactuator means inwardly in said casing will cause said latch means tohold said movable contact means in engagement with said fixed contactmeans and so that outward manual movement of said actuator means willcause said movable contact means to move out of engagement with saidfixed contact means, said means connecting said latch means and saidactuator means permitting relative movement between said latch means andsaid actuator means upon the occurrence of a current overload, and meansmounting said actuator means in said casing for inward movement withrespect to said casing upon the occurrence of current overload,

References Cited in the tile of this patent UNITED STATES PATENTS

